1. Field of the Invention
The present invention concerns a temperature/humidity controller for use in an air conditioner for controlling temperature/humidity of the air conditioner for supplying conditioned air controlled to predetermined temperature/humidity, as well as a recording medium storing temperature/humidity control programs used therefor. More particularly, it relates to a temperature/humidity controller for use in an air conditioner suitable to supply of conditioned air to a coating booth or the like intended to conduct coating under an identical condition while maintaining temperature/humidity at a constant state.
2. Statement of the Related Art
FIG. 8 shows an existent air conditioner 1 for controlling an intaken outside air to predetermined temperature/humidity, in which an outside air intake port 2 is formed to one end and an conditioned air supply port 3 is formed at the other end.
For controlling temperature/humidity of outside air, the air conditioner 1 has temperature/humidity adjusting devices (4, 4, - - - ) including, for example:
a main heater H of a variable heating capacity such as a burner usually referred as a preheater, PA1 an adiabatic humidifier W of a variable humidifying capacity such as a packed bed type air-water contact device or an air washer, PA1 a cooler C of a variable cooling capacity such as cooling coils, PA1 an auxiliary heater RH capable of finely controlling heating capacity usually referred to as a reheater and PA1 an isothermal humidifier DS for conducting isothermal humidification such as a steam injection pipe in this order, along an air flow path from the exit air intake port 2 to the conditioned air supply port 3 in this order. PA1 at least one of temperature/humidity adjusting devices(4, 4, - - - ) including a main heater (H), an adiabatic humidifier (W), a cooler (C) and an auxiliary heater (RH) for controlling temperature/humidity of an intaken outside air are arranged in this order along an air flow path, and further comprising; PA1 the main controller (11) comprises: PA1 a main heating line progressing along an equal absolute humidity line in the heating direction on the psychrometric chart (horizontally to the right), PA1 an adiabatic humidifying line progressing along an equal enthalpy line in the heating direction on the psychrometric chart (obliquely upwardly to the left), PA1 a cooling line progressing toward a cooling temperature set to lower than the dew point for upper limit state point on the psychrometric chart (obliquely downwardly to the left) and PA1 an auxiliary heating line progressing along the equal absolute humidity line in the heating direction on the psychrometric chart (horizontally to the right), in this order.
A roll filter RF is interposed between the main heater H and the adiabatic humidifier W for removing dusts in air. A blower 5 for delivery of conditioned air is disposed to the conditioned air supply port 3.
A temperature sensor T.sub.2 disposed to the exit of the adiabatic humidifier W and a temperature/humidity sensor TH.sub.2 disposed to the conditioned air supply port 3 are connected to the controller 40. The temperature of air after passing through the main heater H and the adiabatic humidifier W is detected by the temperature sensor T.sub.2, and the temperature/humidity of the conditioned air is detected by the temperature/humidity sensor TH.sub.2.
The adiabatic humidifier W is operated at a full power such that air after passing the device reaches 100% relative humidity. The controller 40 conducts feedback control for the capacity of the main heater H based on the detection signal from the temperature sensor T.sub.2, and the cooling/heating/humidifying capacity of the cooler C, the auxiliary heater RH and the isothermal humidifier DS based on the detection signal from the temperature/humidity sensor TH.sub.2.
For instance, if the temperature detected by the temperature sensor T.sub.2 is higher than a predetermined allowable temperature range, the amount of heat supplied from the main heater H is decreased. On the contrary, if the temperature is lower than the allowable temperature range, the amount of heat supplied from the main heater H is increased to elevate the temperature to a level within the allowable temperature range.
Since the adiabatic humidifier W is operated at the full power, air passing therethrough is humidified to a saturated steam pressure line at 100% relative humidity, then cooled to dehumidify to a predetermined absolute humidity by the cooler C based on the result of detection by the temperature/humidity sensor TH.sub.2, and then heated to a predetermined temperature by the auxiliary heater RH, or optionally humidified by isothermal humidification by the isothermal humidifier DS as required, by which the outside air intaken to the air conditioner 1 is controlled for temperature/humidity to finally obtain a conditioned air of a desired temperature/humidity.
In the prior art, when temperature/humidity of the conditioned air is controlled to a predetermined state point on the temperature/humidity line Lo shown in FIG. 9, since air passing through the adiabatic humidifier W reaches the saturated steam pressure line LH exceeding the temperature/humidity line Lo, cooling operation is applied by the cooler C for dehumidification.
Further, even if the air is dehumidified by the cooler C to reach the aimed humidity, since the temperature goes lower than the aimed temperature, it has to be heated further by the auxiliary heater RH.
If the temperature of air after passing through the auxiliary heater RH exceeds the temperature/humidity line Lo, the relative humidity is lowered and, therefore, isothermal humidification is applied by the isothermal humidifier DS. Thus, troublesome and complicated control has been necessary.
As described above, since air conditioning in the prior art requires control process of heating (main heater H).fwdarw.cooling (adiabatic humidifier W).fwdarw.heating (auxiliary heater RH), or control process of humidification (adiabatic humidifier W).fwdarw.dehumidification (cooler C).fwdarw.humidification (isothermal humidifier DS), this results in problems of increasing energy loss and running cost due to the wasteful control process.
If the capacity for each of the main heater H, adiabatic humidifier W, the cooler C, the auxiliary heater RH and the isothermal humidifier DS is put to feedback control individually based on the exit temperature and the exit humidity for each of them, control may be conducted with relatively less wasteful loss.
FIG. 10 shows an air conditioner 1 comprising a capacity setter 41 conducting such control. The capacity setter 41 comprises capacity controllers 42-46 for conducting feedback control of the heating capacity/humidifying capacity/cooling capacity of a main heater H, an adiabatic humidifier W, a cooler C, an auxiliary heater RH and a isothermal humidifier DS individually.
At the input of the capacity controllers 42-46, are connected temperature sensors T.sub.1 -T.sub.4 for measuring the exit temperature of the main heater H, the adiabatic humidifier W, the cooler C and the auxiliary heater RH, and a temperature/humidity sensor TH.sub.2 for detecting temperature/humidity of conditioned air at the conditioned air supply port 3. The controllers 42-46 are connected at the output thereof to the main heater H, the adiabatic humidifier W, the cooler C, the auxiliary heater RH and the isothermal humidifier DS, respectively.
In this improved prior art system, since the capacity for each of the devices is controlled such that the exit temperature for each of them detected by the temperature sensors T.sub.1 -T.sub.4 is identical with a predetermined aimed exit temperature, and the exit humidity of the isothermal humidifier DS is finely controlled based on the temperature detected by the temperature/humidity sensor TH.sub.2, a conditioned air controlled to predetermined temperature/humidity can be obtained.
However, it is not easy to actually determine the exit temperature of each of the temperature/humidity adjusting devices 4, 4, - - - to a specified level at the conditioned air supply port 3 in order to attain predetermined aimed temperature/humidity for the conditioned air. Even if the aimed temperature/humidity is set constant, the exit temperature for each of the temperature/humidity adjusting devices 4, 4, - - - changes if the temperature/humidity of the outside air fluctuate.
For example, in a psychrometric chart shown in FIG. 11, when the temperature and the absolute humidity at the outside air state point X.sub.1 are lower than those at the aimed state point Po for the conditioned air, an operation of heating an outside air by the main heater H and then adiabatically humidifying the heated air by the adiabatic humidifier W is applied, in which the aimed exit temperature for the main heater H is set to t.sub.1.
In this case, if the temperature of the outside air rises to reach the outside air state point X.sub.2, the aimed exit temperature of the main heater H is lowered to t.sub.2. On the contrary, if the humidity is lowered to reach the outside air state point X.sub.3, the aimed exit temperature of the main heater H is elevated to t.sub.3.
By the way, even when the temperature of the outside air is elevated or lowered, if the absolute humidity is equal with that at the outside air state point X.sub.1, the aimed exit temperature t.sub.1 for the main heater H does not change.
On the other hand, when the temperature for the outside air statement point X.sub.5 is higher than that at the aimed state point Po for the conditioned air and the absolute humidity is lower than that at the aimed state point Po for the conditioned air, an operation of adiabatically humidifying air by the adiabatic humidifier W and then cooling air by the cooler C is applied, in which the aimed exit temperature of the adiabatic humidifier W is at t.sub.5.
In this case, when the temperature of the outside air elevates with no change for the absolute humidity to the outside air state point X.sub.6, the exit temperature of the adiabatic humidifier W elevates to t.sub.6. On the other hand, if the temperature is lowered to the outside air state point X.sub.7, the exit temperature of the adiabatic humidifier W is lowered to t.sub.7.
As described above, since the aimed exit temperature for each of the devices changes currently depending on the fluctuation of the temperature/humidity of the outside air and since a relation between the fluctuation of the temperature/humidity of the outside air and the aimed exit temperature is complicate, it is difficult to exactly set the aimed exit temperature by each of the capacity controllers 42-46, resulting in a worry of making the control instable.
In addition, since the capacity to operate each of the temperature/humidity adjusting devices 4, 4, - - - provided to the air conditioner 1 is different depending on the type and the capacity of each of them, so that no stable and efficient control can be conducted by merely controlling each of the temperature/humidity adjusting devices 4, 4, - - - individually.